In the past, operating systems were designed such that applications ran in the same process. As a result, misbehaving applications could take down the entire operating system. Accordingly, modern operating systems put applications into separate processes and restrict access to data between the processes. Thus, if one application crashes, the other applications and the operating system can continue to operate properly.
Browsers may suffer from the same problems as past operating systems. A browser, for example, may allow a user to view pages (e.g., network or content pages, such as web pages) in different tabs. While this functionality is beneficial to the user, any issue with the browser or with a specific tab can take down the entire browser.